diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -5637,9 +5637,12 @@
       // them here.
       break;
 
-    case SUBMODULE_TOPHEADER:
-      CurrentModule->addTopHeaderFilename(Blob);
+    case SUBMODULE_TOPHEADER: {
+      std::string HeaderName(Blob);
+      ResolveImportedPath(F, HeaderName);
+      CurrentModule->addTopHeaderFilename(HeaderName);
       break;
+    }
 
     case SUBMODULE_UMBRELLA_DIR: {
       // See comments in SUBMODULE_UMBRELLA_HEADER
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -2857,8 +2857,11 @@
     {
       auto TopHeaders = Mod->getTopHeaders(PP->getFileManager());
       RecordData::value_type Record[] = {SUBMODULE_TOPHEADER};
-      for (auto *H : TopHeaders)
-        Stream.EmitRecordWithBlob(TopHeaderAbbrev, Record, H->getName());
+      for (auto *H : TopHeaders) {
+        SmallString<128> HeaderName(H->getName());
+        PreparePathForOutput(HeaderName);
+        Stream.EmitRecordWithBlob(TopHeaderAbbrev, Record, HeaderName);
+      }
     }
 
     // Emit the imports.
diff --git a/clang/test/Modules/relative-submodule-topheader.m b/clang/test/Modules/relative-submodule-topheader.m
new file mode 100644
--- /dev/null
+++ b/clang/test/Modules/relative-submodule-topheader.m
@@ -0,0 +1,10 @@
+// RUN: cd %S
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x objective-c++ -fmodule-name=std -emit-module Inputs/submodules/module.map -o %t/mod.pcm
+// RUN: llvm-bcanalyzer --dump --disable-histogram %t/mod.pcm | FileCheck %s
+
+// CHECK: <SUBMODULE_HEADER abbrevid=6/> blob data = 'vector.h'
+// CHECK: <SUBMODULE_TOPHEADER abbrevid=7/> blob data = 'vector.h'
+// CHECK: <SUBMODULE_HEADER abbrevid=6/> blob data = 'type_traits.h'
+// CHECK: <SUBMODULE_TOPHEADER abbrevid=7/> blob data = 'type_traits.h'
+// CHECK: <SUBMODULE_HEADER abbrevid=6/> blob data = 'hash_map.h'
+// CHECK: <SUBMODULE_TOPHEADER abbrevid=7/> blob data = 'hash_map.h'